Search Documents

By N. Dixon

This report summarizes all work performed under U.S. Bureau of Mines Contract J0377014, "Development and Evaluation of Noise Control Techniques for Taconite Processing Equipment." Three areas of taconite processing equipment, grinding mills, fine screens, and crusher screens have been investigated. Extensive noise and vibration measurements have been made on grinding mills in which the process parameters that affect mill noise have been identified, and the level of shell impact noise around the mill defined. A multiplexing telemetry system was used to obtain shell vibration measurements from a rotating mill. Mill noise control methods were investigated and a partial mill barrier was built and tested on a semi-autogeneous mill. A noise reduction of approximately 3 to 6 dBA was achieved on the falling side of the mill. The use of rubber mill liners on autogenous mills has been evaluated. The noise sources on fine screens have been quantified, and noise control treatments developed. Noise reductions of 11 to 13 dBA were achieved at positions around the fine screen and some in-service testing has been done. Noise measurents of crusher screens were obtained and noise control through resilient screen decks appears to hold the most promise. Additional benefits might be lower life-cycle cost, since the service life of resilient decks is claimed to be longer than steel.

Jan 1, 1983

By Anand Bhagwat

Surface control can prevent the falls of ground between primary roof support systems and rib support. Using existing industrial products, and adopting them for mining applications, has historically attained surface control in underground mining. However, the latest innovative solution, a revolutionary wire mesh product, is designed specifically for underground mining applications jointly by Bekaert and Orica. This knotted wire mesh, FlexKnot? 2500 and FlexKnot? 3500, uses smaller gauge, higher tensile strength wires, than a chain link fence or welded wire mesh. The higher tensile wire enables the mesh to achieve greater ultimate load-bearing capacity, with significantly lower overall weight. Test results, obtained at the National Institute for Occupational Safety & Health (NIOSH) Mine Roof Simulator facility, illustrate the comparisons of the new FlexKnot with traditional 8- and 10-gauge welded steel mesh. The FlexKnot is superior in deflection, load-bearing capacity, and stiffness?categories that are critical in achieving safer surface control. It also offers enhanced corrosion resistance because of the galvanized coating applied on the individual wires prior to the knotting process. Case studies from underground coal mine installations confirm that FlexKnot has the ability to significantly reduce installation cycle time and to minimize use and repetitive manual handling of individual mesh panels. An added advantage is the ability to supply FlexKnot in rolls for quick and easy handling for either rib or roof support application. When using rolls, the bolter can install the entire roll with one continuous forward motion, unlike the wasteful back and forth travel for mesh panel.

Jan 1, 2014

By Donelson A. Robertson

Includes a review of the state-of-the-art of explosives loading in the crushed stone and cement industries of South Florida and the development of a field test program for alternatives. Emphasis is on the loading of small diameter (2 1/4" or less) explosives. Test results ire evaluated for operational and economic feasibility. Details are described of an explosives loading method which involves placing cardboard tubes with external couplings through the hollow drill steel and then Loading explosives into the tube casings after the drill rig has moved off. This method eliminates the hazards peculiar to loading explosives Through the kelly bar. The alternative method can be performed by existing drill rigs with or without minor modification. With modification, improvement in yield per blasthole and/or primary crushing rate provides opportunity so offset some or all of the additional cost.

Jan 1, 1978

By C. L. Wilsey, K. M. Oakes, W. J. Reich, M. J. Protani

The time frame required to complete the National Environmental Policy Act (NEPA) process for a new mine, or for the expansion of an existing mine, can range between 9 months to 24 months, or more. The time frame will vary depending on whether an Environmental Assessment (EA) or an Environmental Impact Statement (EIS) will be completed. Completing properly designed baseline studies to collect natural resource data to support the EA or EIS prior to the start of the NEPA process can shorten this time frame. The two year natural resource baseline study completed by Homestake Mining Company for the Ruby Hill Mine, located in Eureka County, Nevada will be used as the case study to describe how properly designed and executed natural resource baseline studies streamlined the NEPA process.

Jan 1, 2001

By Carl Lee

CHICAGO in the last week of June fulfilled all its promises to the visiting engineers except one. This holds true with respect to the activities of the Regional Meeting of the A. I. M. E. in particular and of Engineers' Week in general. No one expected to find much of the beautiful in the outward aspects of the Fair-the Century of Progress Exposition, to be more formal; but they expected novelty, color, and startling lighting effects at night, and they were in no sense disappointed. It has been said that the architecture is a portent of the style of the buildings of the future; most who have seen the Fair hope that this forecast will prove inaccurate. As to the exhibits themselves, they are splendid. They are in keeping with the theme of the Exposition-a Century of Progress in science, in engineering, in the industries based upon them. No attempt will be made here even to suggest the exhibits that are most interesting. There are plenty for every one; and any member of the Institute who has the opportunity should by all means visit Chicago before the end of October.

Jan 1, 1933

By Roger A. Bullivant

The introduction of this size and type of piling rig is intended to address a multipurpose foundation activity. The 8000 denotes the size of equipment that is attached to the mast, namely 8000 Kg. Larger equipment can be carried subject to adjustment of rig geometry. The 8000 series rig will easily accept hydraulic piling hammers and CFA equipment, but for the purpose of this discussion it will be equipped with an auxiliary power pack that is matched to twin vibrators. The design of the siamesed vibrators allows long tube equipment or piles to be driven with a short mast configuration that provides a lower overturning risk. It is easily adapted within minutes to carry out other foundation requirements that are required on the same contract. The piling and ground consolidation activities that can be undertaken by the 800 series machine are:-

Jan 1, 1995

By A. Redman

Aquatic organisms are sensitive to free cyanide (HCN) though the presence of certain metals that can form stable complexes and thereby reducing both the amount of bioavailable cyanide. Recent work has suggested that consideration of HCN rather than total cyanide can provide the basis for water quality criteria. Cyanide is often present in complex effluents that affect speciation and bioavailability. We have developed a model to predict the speciation of cyanide in complex effluents and have shown that this model can predict the toxicity of metal-cyanide complexes in terms of HCN. This study evaluated available cyanide toxicity exposures with this model to assess the role of water chemistry (e.g., metal-cyanide interactions) on the observed. Toxicity endpoints based on total cyanide ranged over several orders of magnitude for a variety of metal-cyanide mixtures. However, predicted HCN concentrations among these same tests described the observed toxicity data to within a factor of 2. Aquatic toxicity can be well described using HCN though in certain metal-cyanide mixtures toxicity was jointly described by HCN and elevated levels of bioavailable metals. This work was performed in support of an industry-sponsored reassessment (Gensemer et al 2006) of the U.S. EPA water quality criteria for cyanide (EPA 1985) using free cyanide as the basis for the re-calculation. The work presented in this manuscript presents technical support for using free cyanide as the preferred basis for this recalculation.

Jan 1, 2011

By P. S. Baker

CRU estimates that the global supply of metallurgical grade alumina (MGA) grew by 5 percent during 2005 to a little more than 61 Mt (67 million st). About 30.7 Mt (33.8 million st), or 50.3 percent, of that originated from Oceania (principally due to the commissioning of the CAR refinery in Australia) and Latin America. In this context, Chinese production surged by 20.5 percent year-on-year to 7.7 Mt (8.5 million st) on the crest of a 17-percent rise in that country’s primary aluminium production. Meanwhile, on the demand side, there was a 6.7 percent climb year-on-year in global consumption to 62.3 Mt (68.6 million st). This reflected a healthy demand for primary metal from aerospace, construction, packaging and passenger transportation (to a lesser degree) in the United States, China, Brazil, South Korea and India. So there was an overall supply deficit of more than 1.2 Mt (1.3 million st). This, combined with an 18.3-percent diminution in closing stocks (down to 35 days of requirement), lifted the average spot price of MGA by 17.6 percent year-on-year to US$448/t (US$406/st).

Jan 1, 2006

By Charles L. Kimbell

For the world mineral industry as a whole, the year 1981 was a period of continuation and, in some instances, an acceleration of negative trends extending back into 1980. Most available statistical data reflected stagnation or downturns in activity. Levels of production, trade, and consumption declined for a substantial number of leading mineral commodities, including, most notably, steel and petroleum. Investment, if not lower than in 1980, was evidently increasing at a more modest rate. Prices for major mineral commodities were generally lower, at least in terms of constant dollars, and in some cases even in terms of current dollars. Prospects of a major reversal of these patterns seemed dim. The mineral industry, however, was far from alone in this general downturn; most other elements of the national economies of the world's nations fared little better. General conditions of inflation, recession, and reduced industrial product consumption were reflected in most other sectors of the total economy. International political events continued to influence mineral output and flow but had less influence on overall levels of activities than on the geographic distribution of these activities. The Iran-Iraq war certainly played a role in reducing mineral industry activities in those nations, but the commodity most affected, petroleum, was available from other sources in sufficient quantity that, in the face of reduced demand, a substantial surplus developed.

Jan 1, 1983

By H. G. Rushton, A. S. Romaniuk

"The opening chapter of this volume, by A. Ignatieff, places in perspective Canada's coal resource base as part of the world scene. This chapter will focus on the Canadian scene.Units of measurement in this report are in the International System of Units (SI) as approved for official use by the Canadian Standards Association and Metric Commission Canada. These units have been adopted by the Mining Association of Canada and the Coal Association of Canada. To assist with the shift to metric units these two associations have published ""Metric Practice Guide for the Canadian Mining and Metallurgical Industries"", 1978(1J, Appendix ""A"" lists some useful conversion factors along with SI prefixes. The last official assessment of Canada's coal resources and reserves was done by the Department of Energy, Mines and Resources and presented in Report ER 79-9 ""Coal Resources and Reserves of Canada"", published in December 1979 and authored by H.U. Bielenstein, L.P. Chrismas, B.A. Latour and T.E. Tibbetts(2). The Geological Survey of Canada has a continuing project concerned with coal resource assessment as does CANMET, whose concern is with coal reserve assessment and coal quality. As well, Alberta's Energy Resources Conservation Board (ERCB) has a continuing assessment program for coal in Alberta and publishes an annual reserves report, the current issue of which is cited as reference No. (3). The difference in resource and reserve terminology as used by EMR and ERCB has a major effect on derived tonnages for Alberta. This difference will be discussed later. In 1982 the Department of Energy, Mines and Resources produced a map titled ""Canada-Coal""<4J which outlines coalfields and illustrates coal import and export movements for the years 1981and1980. A copy of this map is contained in the map pocket of this publication. Two other resource assessment reports are noteworthy, the first is ""Coal Resources of Southern Saskatchewan: A Model for Evaluation Methodology"", by J.A. Irvine, S.H. Whitaker and P.L. Broughton<SJ which is one of the major outputs of a joint federal-government study of southern Saskatchewan's lignite deposits. (Another output from this same study' is the Geological Survey of Canada's SASCO file, a computer processable file holding borehole and coal quality data.) The second is ""Deep Coal Resources of the Interior Plains, Estimated from Petroleum Borehole Data"", by G.D. Williams and M.C. Murphy(6) which identifies coal resources from nearly 4,000 petroleum exploration boreholes distributed uniformly over an area spanning Manitoba, Saskatchewan, Alberta and British Columbia."

Jan 1, 1985

By I. R. Firth, D. L. Taylor

The ability to accurately model the movement of grade boundaries during a typical bench blast would be of significant benefit to mine operators. The movement of grade boundaries during the blasting process may have significant impact on grade recovery if not accounted for. The paper describes the preliminary stages of a research project which combines numerical blast models and conventional mine planning software to allow practical use of the results of a numerical blast simulation. A two dimensional bench blast is simulated using the Universal Distinct Element Code (UDEC). The results of the simulation are used to provide input to the Surpac mine planning package which can be used to generate grade control plans.

Jan 1, 2001

By K. N. Santini, J. M. Barker

The perlite industry in the United States continued to undergo rapid change and increased competition last year as it did in 2002. U.S. production in 2004 was 510 kt (562,000 st),an increase following five consecutive years of decline (Table 1). Perlite is exported to Canada and to the Pacific Rim. These partially offset imports. Perlite imports from Greece to the eastern and Gulf Coasts of the United States declined by about 22 percent after reaching a record 240 kt (264,000 st) in 2003.But their market remains protected by high rail rates from western U.S. plants. Minor imports of perlite persist by Termolita from Mexico.

Jan 1, 2005

By S. M. Pickering, L. T. Gregg

Appraisal of industrial minerals beneath privately owned land requires a different approach and mindset from valuation of base and precious metals or energy minerals, and from valuation of government-owned mineral lands. First, is it the value of inground minerals or of mining rights that is being sought? Second, value to whom, the mining company, a potential investor, the mineral landowner, a lending institution, the property tax assessor, or a condemnor? Third, how should mineral value be apportioned between the land and mineral owner, and a mining company with limited years of lease-hold interest? These and many other questions must be addressed before a valuation method and Discount Rate are selected. For various reasons the Income Method is most often used, with Net Present Value calculations made for long term predicted mining income. Choice of an appropriate Discount Rate is critical.

Jan 1, 2000

By Russell D. Melton, Gary A. Kanelos

A construction company performed blasting operations to break up limestone bedrock for excavation of residential basements. The owners of an existing residence located approximately 400 feet from the operation claimed that vibration damaged the structure and created foundation subsidence by lowering the moisture content of the foundation soils.

Jan 1, 1996

By CHARLES L. WRIGHT

Coals may be divided into six classes-anthracite, semi anthracite, semibituminous, bituminous, subbituminous, and lignite. The first three cla~ can be distinguished by dHferences of composition, particularly the proportions of fixed carbon and the ratios of the fixed carbon to the volatile matter in the cools. The last three classes can be distinguished by di:fferences in physical character, chiefly in color and in manner of weathering. Lignite is brown, not black, and has generally a woody look, but it weathers in much the same way as subbituminous coals. On exposure to the air lignite slacks or crumbles. The lumps check and fall into small irregular pieces that exhibit a decided tendency to separate into extremely thin plates. Hence lignite deteriorates greatly during storage or long transportation. The most characteristic feature of the composition of lignite is a large percentage of moisture. '!his high moisture content reduces the fuel value of freshly mined lignite, and the partial evaporation of moisture, on expooure, causes th6 fuel to check and fall to pieces. Consequently, attempts to increase the efficiency of lignite as a fuel involve reducing its percentage of moisture and increasing its ability to endure storage and transportation. Both these results are accomplished by briquetting.

Jan 1, 1911

By Roger G. Sprague

With the passing of time, changing marketplaces and years of hard service, coupled with new machines, increased productivity, rapidly improving technology, equipment which used to be the latest in modern mining have now slipped into obsolence. Mining companies need reliable, productive equipment in order to compete in today's market. In Western coal mining, as coal seams become deeper, older equipment must be replaced with that which can do the job more efficiently.

Jan 1, 1998

By L. E. Cardwell

This publication contains routine analyses and related source data for 377 natural gas samples from 19 States and two foreign countries. Of this total, 373 samples were collected during calendar year 1970. The remaining four samples were collected during previous years, but releases granting per-mission to publish the analyses were not received until 1970. All samples were collected as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Twelve previous publications have presented the results of 9,050 gas analyses prior to 1970. The first three, Bulletins 486,6 576,8 and 617,7 contain analyses and related source data on 5,218 gas samples collected from

Jan 1, 1971

By R. C. Milici

The primary factors that determine the marketability of coal from various supply centers in the U.S. are coal quality and supply; i.e. low sulfur, moderate- to high- Btu coals have large market areas when compared to less expensive but poorer quality coals. Price is the major factor in the competitive marketing of similar coal products. Good quality, (moderate- to high- Btu, low sulfur) coals from the Powder River and central Appalachian basins are marketed over large areas of the country, and central Appalachian coal is widely distributed in foreign markets, primarily as coking coal. In contrast, poorer quality bituminous coal (low calorific value and/or high sulfur) from the Illinois Basin, northern Appalachian Basin, and lignite from the Gulf Coast is marketed in or near the States in which it was mined even though the price at the mines may be lower than mine prices for central Appalachian coal. Widespread distribution of sub-bituminous Powder River Basin coal is enhanced by its exceptionally low mining costs, which offsets transportation costs to distant markets.

Jan 1, 2001

By A. J. C. Paterson

High density slurry and paste tailings systems offer significant environmental benefits primarily related to reduced water consumption. However, these potential advantages need to be evaluated on a project-by-project basis. The successful design of a thickened or paste tailings system requires that the system is designed to accommodate the effect of the high density slurry on pumps, pipelines and the overall system operation. The transport system must be designed as an integrated unit and the interaction of all the components need to be considered. The transport system includes the slurry preparation plant, the pump station and the pipeline. This paper assesses the impact of increasing the slurry density in a platinum tailings system from conventional densities to thickened and paste tailings densities. As slurry density and rheology increase, there is a sharp increase in energy consumption for the additional water savings and this additional cost needs to be considered. A case study shows that there is a considerable benefit in increasing densities to the point at which tailings can be still be deposited in the standard manner. For existing systems, increasing density can result in an increased capacity at a marginal power cost, provided that the slurry is not too viscous. For a new system, a smaller pump and pipeline can result in lower capital costs and a marginally higher energy cost, if the optimum density is selected. Keywords: tailings, paste, pumping, slurry

Jan 1, 2004

By H. D. Raymond

This report contains a summary of designs, specifications, costs, and schedules developed for a prototype oil-shale demonstration mining program to be undertaken at the Horse Draw site in the Piceance Creek Basin, Rio Blanco County, Colorado. The objective of the demonstration program is to assess the feasibility of extracting oil shale and associated saline minerals from deep, rich oil shale zones which occur within the central portion of the Basin. Four mining systems were specified for demonstration. These include (1) chamber and pillar mining with backfill; (2) sublevel stoping with backfill; (3) sublevel stoping with full subsidence; and (4) block caving. Commercial-scale designs for each system were modified and scaled down as required to achieve program objectives. The demonstration mine layout and design includes specifications for ore handling, backfilling, ventilation, dewatering, maintenance, and supply systems. A feature of particular interest in the design is the combination of block caving and sublevel stoping methods into a single unit for demonstration of subsidence mining systems in deep oil shale deposits. The report also contains a detailed breakdown of projected capital and operating costs for the demonstration mining program.

Jan 1, 1979